Mount St. Helens, 40 years later: Looking back, ahead on anniversary of worst U.S. volcanic disaster

Effects of blast still being felt to this day

Monday is a day for the history buffs.

The day marks the 40th anniversary of one of the worst natural disasters in U.S. history, when Mount St. Helens, located in southern Washington state near the Oregon border, erupted.

To this day, it is still the biggest volcanic eruption in U.S. history, and its effects are still being felt to the surrounding environment four decades later.

How it all happened

In March 1980, a series of earthquakes shook around the grounds of Mount St. Helens, raising fears that volcanic activity was imminent, according to Live Science.

Mount St. Helens hadn’t had any activity at that point since the 1840s and 1850s.

On March 27, the peak of the mountain burst open, shooting steam into the air and creating a 250-foot-wide crater through the summit, according to USGS.

On May 17, the north side of the volcano bulged out 450 feet horizontally, indicating that magma was rising toward the summit.

The next morning, a 5.1-magnitude earthquake was registered 1 mile beneath the volcano, causing USGS volcanologist David Johnston, who was stationed roughly 6 miles from the volcano at a campsite, to say “This is it” in a radio message, according to Live Science.

It turned out to be Johnston’s last transmission.

Seconds later, the blast occurred.

The damage done

When it was all said and done, the blast resulted in the following carnage:

  • 57 people were killed
  • An estimated 540 million tons of ash drifted into the air and settled over seven nearby states.
  • Hundreds of square miles of land were reduce to wasteland, causing roughly $1 billion in damage.
  • Thousands of animals were killed.
  • More than 200 homes were destroyed.
  • More than 185 miles of roads and 15 miles of railways were damaged.
  • Sewage systems were clogged.
  • Spirit Lake, a popular tourist and recreation destination nestled below the mountain, was covered in ash and debris. Its bed was raised 200 feet.

What does the future hold?

The damage done to Spirit Lake is still being felt to this day, and has caused some nerves going forward, according to Yahoo.

There is roughly 73 billion gallons of water in the lake that is being held back by debris caused by the explosion.

There’s no natural drainage -- and a 1.6-mile tunnel was built in 1985 to offer a relief valve for the lake, but faults and subsidence deform that valve repeatedly.

If there’s another major earthquake or disaster, the water could push through, and cause incredible flooding to nearby cities.

Then, there’s the matter of the volcano itself.

Mount St. Helens figures to erupt again at some point, but of course, predicting when is virtually impossible.

Certainly, when America woke up on this day 40 years ago, nobody could predict the tragic history that was about to unfold.

About the Author:

Keith is a member of Graham Media Group's Digital Content Team, which produces content for all the company's news websites.